Elastomeric Networks, and Their Use in Novel Nanocomposites and Related Materials

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TECHNICAL SUMMARY:One practical goal of the research being carried out is to obtain structure-property relationships that can be used to optimize the properties of elastomeric materials. Experiments will include a variety of deformations, and corresponding computer simulations will be carried out as well. Elastomers will include commercially important polymers, cross linked by a variety of techniques. One specific project will be producing biodegradable elastomeric gels of enhanced orientation and improved mechanical properties. Another example involves characterization of strain-induced crystallization, which can greatly improve the mechanical properties of a material. Novel reinforcing fillers such as silica will be generated in-situ, yielding unusual particle shapes and orientations, and ceramic particles of one type will be coated by a ceramic of another type. It will also be possible to thread elastomeric chains through reinforcing zeolites, to obtain other unusual properties. Simulations will also be carried out to elucidate reinforcing mechanisms in filled elastomers in general, which is one of the major unsolved problems in this area of polymer science. Of particular interest here is the types and extents of reinforcement obtained when the primary particles are bonded into relatively stable structures called "aggregates" and into less-stable arrangements called "agglomerates". As a final topic, experiments will be carried out to exploit the ability of elastomeric domains to improve the impact resistances of polymer-ceramic hybrid composites in which the ceramic is the continuous phase. Of particular interest in this regard is control of the level of dispersion by using the connectivity of network structures in one of the phases to "frustrate" the usual types of phase separation in disparate two-component systems. NON-TECHNICAL SUMMARY:The work described will provide a better understanding of polymers in general and elastomers and nanocomposites in particular. This will ultimately lead to guidance important for the preparation and utilization of better elastomeric materials and various types of composites. Results will be disseminated in the usual way, in journal publications and lecture presentations at National Meetings of various scientific or engineering societies. Broader impacts, would include integrating research and teaching. The rubberlike elasticity exhibited by elastomeric materials is one of their most striking features, and the applicant will continue to exploit this in demonstrations during lectures, experiments in laboratory courses, and in the modification of standard physical chemistry concepts. Results from experiments, simulations, and theory obtained in these projects will continue to be included in the elasticity course taught at the University of Cincinnati, and in some of the American Chemical Society Short Courses the applicant has taught since 1972.